Instead of having separate water and ice types, would it not make sense to simply have "ice" or cold based attacks? I have always wondered how water by itself could actually damage things...like the "water gun" move in Pokemon. Some moves like "hydropump" might cause damage simply by virtue of the sheer amount of force that a waterfall would have, but that is a function of kinetic energy not necessarily innate to water itself. Ice based attacks do make sense, however because severe cold causes problems for many creatures.

Anyway, I really like this sandworm creation of yours, especially because it is eyeless and I like monsters that lack visible eyes. In one of the "vomiting" attacks, it vomits a green substance. Is this some sort of venomous compound, or is it actually "blood" since one of the "damage" animations that the sandworm has shows that it has green blood. Finally, how about a ramming attack where the worm lowers its head and rams the enemy using its large mass as a battering ram? Also, how about an attack where it will tunnel under an enemy and pull it underground?